Means for controlling inductive heating



April 1943- F. s. DENNEEN ETAL 2,315,508

MEANS FOR CONTROLLING INDUCTIVE HEATING Filed may 27, 1940 I N VE NTOR5 Patented Apr. 6, 1943 2,315,508 MEANS FOR CONTROLLING mnuo'rrvn HEATIN Francis S. Denncen, Cleveland, and William C. Dunn, Shaker Heights, Ohio, assignors to The Ohio Crankshaft Company, Cleveland, Ohio, a

corporation of Ohio Application May 21, 1940, Serial No. 331,423

3 Claims.

The present application is a continuation-inpart of our co-pending application for Apparatus for progressive heat treatment, Serial No. 745,194, now Patent No. 2,202,758, issued May 28, 1940, filed September 24, 1934, and renewed November 9, 1938, and is directed to apparatus for heat treating elongated metallic articles of varying form. The former application is concerned primarily with the use of rigid inductors or inductors formed from rigid elements. In the pres ent case a flexible inductor as shown in the former application is described.

It will be obvious if an attempt is made to pass an article into an inductor of fixed form which is too small to receive the entire article thatthere will be a part of the article in which desired heating will not be accomplished. For instance, when approaching a limiting position on the article, such as a shoulder, where only a part of the inductor would come into heating relation witl'-..the article a change in the form of the inductor is needed to concentrate more current in the region affected by the limited movement.

When a deficiency in heating tends to be caused by a lack of sufliclent ampere turns of the inductor in the region of the part of the article to be heated, the deficiency can be overcome by deforming the inductor to bring a remote part of the inductor closer to the part of the article or to otherwise increase the concentration of magnetic flux in the desired region.

The principal object of this invention is to provide an inductor which is readily deformed to concentrate magnetic flux to a predetermined extent in a selected part of a progressively heat treated article. A further object is to provide means for deforming the inductor while a part of the article moves past the inductor. A still further object is to provide an inductor constructed to maintain its general form while varying in size. An additional object is to Provide conveniently associated means for quenching the article being heated by current induced therein.

While in the accompanying drawing and specification we have illustrated and described our invention as applied to certain purposes, we do not limit ourselves to the constructions shown and described. From the disclosure herein, obviously, many modifications and other uses would readily suggest themselves to those skilled in the art.

In the annexed drawing the sole figure is an elevation of the preferred form of our invention. In this preferred form the apparatus is adapted to automatically regulate heating as the heating progressively approaches a shoulder of a shaft or other cylindrical form. The heating element or heater is made in the form of a flexible and variable helix as shown at N. Suitable current is supplied at the terminals II and I2. This helical conductor is supported by the quenching ring l3, suitable insulation being employed as at H. As the cylindrical article l5 passes into this helix it is heated by the coils and as it emerges is quenched by fluid flowing from ring l3 through orifices l6. When shoulder I'I enges the upper part of the helix through insulation l8, the helix is compressed automatically such as by the weight of the article l5, and more and more heating is concentrated adjacent to the shoulder causing the depth of heating to become equalized. At the time the spaced coils reach a substantially closed relationship the heating is completed. The heated surface above ring l3 can then be quenched by any suitable means.

Other modes of applying the principle of our invention may be employed instead of the one explained, change being made as regards the means herein disclosed, provided those stated by any of the following claim or their equivalents be employed.

We, therefore, particularly point out and distinctly claim as our invention:

1. In apparatus for hardening a surface zone of an article adapted to be hardened by heating and quenching, a helical conductor adapted to surround a part of the article and to lie in spaced relationship thereto, means for supplying periodically varying current to the conductor to induce heating current in the surface zone, and means for compressing the helical conductor axially to reduce the length of the helix and to concentrate the induced current in a selected part of the surface zone.

2. In apparatus for hardening a surface zone of an article adapted to be hardened by heating and quenching, a helical conductor adapted to surround a part of the article and to lie in spaced relationship thereto, means for supplying periodically varying current to the conductor to induce heating current in the surface zone, and quenching means being associated with the conductor, said quenching means serving as means for compressing the helical conductor to control a distribution of magnetic flux in the aforesaid surface zone.

3. In apparatus of the class described, a flexible conductor having a coil adapted to encircle a part of an article to be heat treated, means for supplying periodically varying current to the conductor, and quenching means, the quenching means serving as means for flexing the conductor to vary a concentration of' magnetic flux in a surface zone of the article.

- FRANCIS S. DENNEEN.

WILLIAM C. DUNN. 

